Tools & materials required

Safety first

We recommend undertaking any decking project with the help and assistance of a friend.

Always wear protective safety gear when necessary.

If securing your decking with footings, make sure there are no cables or pipes underneath where you want to dig. Rent a cable avoidance tool (CAT) to conduct these checks and if found, we suggest reconsidering your decking plans. Or consider installing a hinged trap door in your decking to allow future access to the area.

Don't burn the off-cuts of pre-treated timber decking as the smoke and ash produced is toxic. Dispose of them as you would ordinary household waste.

You might need

The following list of tools and materials includes everything you will need to lay a basic, ground-level deck. Some items are needed for multiple stages in the process, but are only listed once, so be sure to check the steps for further detail.

To lay timber deck boards

Decking screws - we recommend choosing screws that are at least 2.5 times longer than the surface they'll be secured to (the deck boards). And if laying Grassedeck boards, opt for green-coated decking screws to minimise the appearance of the screw heads.

Step 3a

Choose what surface your decking is going to be laid on. There are two options when building on soft ground:

add concrete pads for extra stability

or lay straight onto the ground for a simple project

We recommend adding concrete pads as they're not only great for stabilising your deck; they'll ensure your decking lasts longer.

If laying straight onto the ground, jump to Step 3b.

If you’re adding concrete pads

It's key that the concrete pads are positioned in the exact places and that they're all square for the deck joists. For help on this, head to the 'How to square a site' section of our How to build a raised deck article for more advice.

Work out where exactly the pads are required and dig holes roughly 150mm square and 150mm deep at intervals of 1.2m around the deck.

Fill the holes with a quick-drying, ready-to-use concrete to just above ground level. Use a spirit level and straight edge to check that the pads are level with each other, and if not, use a brick trowel to level off the highest points while the concrete is still semi-dry.

When the concrete has hardened off (is completely dry), cover the whole area with weed control fabric (making cut-outs for the concrete pads) and a layer of gravel (40 to 50mm in depth).

Cut and lay squares of damp-proof course to sit between the concrete and the deck joists.

Step 3b

If you’re laying straight onto the ground

Cover the area in a layer of weed control fabric and then 40mm to 50mm of gravel.

How to cut deck boards

Both timber and solid composite deck boards are cut in the same way. We recommend the following products based on the scale of your project.

Lots of cuts: Use a mitre saw (also known as a chop saw). The diameter of the saw's blade determines how wide and thick the cutting material can be. When cutting solid composite boards, we recommend a 254 to 305mm saw blade with 40 teeth or less for the best results.

A few cuts: Use a panel saw.

Fiddly cuts: Use a jigsaw. They're ideal if there's a shape to cut and work well cutting notches and curves in deck boards around obstacles such as posts.

Deep cuts (the timber is thicker than the cutting depth of the mitre saw): Use a panel saw if only making a few cuts, or a circular saw if making lots of cuts.

When cutting Walksure or Grassedeck boards, check that the decorative surface is facing up when you’re cutting them. Don’t worry about the surface lifting - it’s glued down with several continuous lines of glue, so the risk of this lifting is minimal.

Step 1

Measure and mark the deck board at the desired length.

Use a combination square to mark an accurate line across the deck board. Measure twice before cutting.

Step 2: If using a jigsaw

Clamp the deck board, face side up, in a workbench and slowly cut along the line.

Don't go too fast when using a jigsaw or the cut might not be as straight as you want it.

Step 3

Apply a protective treatment to any cut or recessed timber - be it deck boards, joists or posts - before assembling.

This is applicable to all timber, including Walksure and Grassedeck boards. There's no need to sand or treat solid composite deck boards

How to assemble your sub-frame

The following instructions show you how to assemble a sub-frame. These steps are necessary for laying both timber and solid composite deck boards.

Even a small deck will be very heavy, so do build it on site and remember when measuring and cutting the outer joists, that the timbers will overlap at the corners.

Top tip: Work around existing features

Don’t cut down a tree - build your deck around it by including a bit more sub-structure to frame the trunk. Block off the area around the tree by positioning joist off-cuts between the inner joists, secured either end with two coach screws. Then cut and fix the deck boards to fit around the tree. Remember to leave enough space for the tree trunk to thicken and for it to sway in the wind. And consider or research the species as some trees can by very fast growing.

Step 1

Before you commit yourself to the build, it’s a good idea to do a dry run of the decking first as you don't want to finish the last row with a thin slither of deck board.

Lay out the joist frame and position the deck boards on top, creating the necessary deck board expansion gaps.

Timber deck boards require a 5 to 8mm expansion gap along the length of the deck boards and a 3mm gap along the ends of the deck boards.

Solid omposite deck boards require a 6mm expansion gap along the length of the deck boards and a 3mm gap along the ends of the deck boards.

A gauge screw makes an ideal spacer or use off-cuts of wood. And check that all gaps created are the same for a uniformed finish.

If the deck boards on the end row overhang the joist frame, consider increasing or reducing the expansion gaps of timber deck boards by the recommended amount. This isn't possible for solid composite deck boards as they have one standard size of expansion gap. Alternatively, shorten or increase the outer frame so that your final decking row will finish flush to the edge of the joist frame.

Work all this out before you cut and assemble the deck frame or add concrete pads.

Step 2

Measure your deck frame and cut to size.

Step 3

Make two pencil marks on each end of the deck frame's two outer joists - these are at right angles to the inner joists. These marks are where the coach screws will go. Make the marks to align with the centre of the adjoining outer joist. This will total eight marks - two in each corner of the outer joist frame.

Use a flat wood bit to drill recesses into each of the eight marks. These should be the depth of the screw's head and wide enough for a ratchet or socket attachment to tighten them. Also known as countersunk holes, these recesses ensure the screw heads will be flush with the joist surface for a neat finish.

Step 4

Replace your drill bit for one that's thinner than your coach screw's shank. Line up the adjoining outer joists and drill a pilot hole through the centre of the recess, from the outer joist into the adjoining outer joist. A pilot hole provides a guide hole to help direct the screws and prevents the screw from splitting the wood.

Top tip: Conceal joists

Top tip: Joining joists

If you're extending your deck further than the length of a joist, clamp the joist sections end to end in a workbench.

Place a joist off-cut about 600mm long across the join, and clamp it temporarily to the joists. Secure it with eight coach bolts sunk from the outside of the frame.

When joining lengths of internal joist (which will be hidden by the deck boards), use two 600mm sections of joist off-cut sandwiched either side of the join for a stronger fix.

How to lay timber deck boards

The following step-by-step instructions show you how to lay all timber deck boards, including Walksure or Grassedeck boards.

Step 1

Start in one corner of your sub-frame and position the first board across the inner joists, so that the deck board is in the opposite direction to the inner joists. The board should be positioned flush with the frame.

Position any end to end joins between the deck boards halfway across an inner joist so that both boards can be screwed into the joist for extra stability.

Mark a cutting line for the end of the first board and cut it to fit.

Don’t forget to allow for an expansion gap of 3mm in your measurements when the boards are butted up end to end.

Step 2

The deck board has to be secured to every joist it covers over along the sub-frame. Use two decking screws where each board meets a joist.

Mark the screw locations in pencil, ensuring that they're at least 15mm from the end of the board and at least 20mm from the outside edges.

There's no need to create recesses or countersunk holes for the deck screws, as they're designed to create their own recess when screwed down for a flush finish.

We recommend drilling pilot holes for the screws to help prevent the wood from splitting. Select a drill bit for your drill driver that's thinner than the deck screw's shank and drill pilot holes into the pencil marks - being careful to drill through the deck board and not into the joist.

Screw the decking screws into the pilot holes.

If laying grooved deck boards facing upwards, position the screws at the bottom of a groove.

How to fit solid composite deck boards

Fitting solid composite decking doesn't require any specialist tools – you can use the same as if you were fitting a timber deck - the fixings just require a different technique. The grooved side edges of solid composite boards accommodate a hidden fastening system, which allows for a smooth finish across the deck floor.

Like timber decking, solid composite boards require expansion gaps. The hidden fastening system creates a uniformed 6mm expansion gap between boards when fitted width to width, and a 3mm gap fitted end to end. And remember that if you’re fitting solid composite decking next to a wall, you’ll need to leave a minimum of 10mm gap there too.